I've been asked by a member of this newsletter list to comment on acoustic guitar
pickups. I'll oblige by discussing my own approaches, priorities and prejudices, and
invite folks to reply with theirs, if they wish. I hasten to admit that I am not an expert
in electronic sound processing, so it is fully possible that I may misspeak herein on
specific details of science or electronics. However, my approach is from the vantage point
of an experienced installer and lay observer, so you will probably find what I have to say
more useful than if you were to get a techie to talk to you.

The paramount considerations in selecting a pickup system are at least three:
Which system will physically fit into the instrument; what will the user's performing
environment be and how much the user wants to spend.

SUITABILITY
The first puzzle is, which unit will physically suit the instrument? I personally have to
deal with more arcane requirements than most of you out there, since I get to service a
wide gamut of world instruments. I deal with ukeleles, cavaquinhos, charangos, tiples --
instruments which, if you're lucky, you can get several fingers into the soundhole. Let
alone an arm holding a pickup. Indeed, I once had to prepare a Saz with a pickup, a
turkish instrument with no soundhole at all! And there are those outsized Mexican
guitarrones with the medieval tie blocks. Like the guitarron, many of these traditional/
folkloric instruments have no saddle, so saddle transducers are out. But for the average
installer, more pressing problems are: can I get my arm in there? and, if the user wants
to control the sound output of the unit, do they want to cut out a large hole in their
instrument to access the controls directly--or not?

BUDGET
The second consideration, the user's budget must be evaluated realistically in terms of
what the user's expectations are. Generally, the price of a pickup system increases as a
direct proportion to the system's fidelity to the actual sound of the guitar, and to the
number and convenience of its controls. If the natural sound of the guitar to be picked up
doesn't exactly warrant super-authentic duplication, then the user is wasting money
purchasing an advanced, high-fidelity system. If the user can dispense with controls
completely (that is, doesn't mind walking up to the amp to adjust the sound) a good 50% of
the total system cost can also be dispensed with. Often a user with too large a budget
will buy all the bells and whistles and come to find them too encumbering and impractical
for their actual guitar-playing environment. One player I know dropped $400 on a Fishman
Blender box when all he really needed on stage was a volume control, and besides while
playing on a live stage surrounded with percussion and electric guitars, he had to turn
down his internal microphone so much that it hardly was worth the trouble to have a
pickup/microphone combination at all. He actually had better results shutting it off
altogether. The expensive blender ended up in a heap of dust in his garage.

PLAYING ENVIRONMENT
The third consideration, the player's environment is perhaps the most important. The
playing environments of my customers fall into several distinct categories. The simplest
requirements are those of the lone player: a guitarist simply wants to plug the guitar
into an amp in a room, preferring to listen to the acoustic instrument through an
amplifier. Playing a lone acoustic guitar amplified in a room is a perfectly valid
creative endeavor: an amp offers an expanded dynamic range and the potential of a wide
range of electronic colors added to the players' tone palette. More power to them.

Next, consider the same lone player in a studio recording situation: the prime
requirement for this is usually the most complex: maximum information is required. The
recording engineer often wants as much of the total sound that the guitar is producing as
possible, so that all the nuances are available for processing. And although many
recording engineers are adept into turning an aural pig's ear into an aural silk purse,
most will tell you that they would prefer to begin with a good guitar attached to a good
pickup system, than have to waste their time applying cosmetic fixes. Fidelity is key in
this environment.

The next category is the stage environment, and here there are usually three
sub-categories: the solo performer, the performer as part of a low-key ensemble and the
performer who is part of a loud, heavily amplified ensemble, band or orchestra. Each has
important and distinct requirements which I will cover shortly.

Let me preface the following, if you haven't already noticed, by pointing out that
I'm carefully avoiding the word "transducer," ordinarily and loosely used to
denote a strip pickup which is put under the saddle in the bridge. I don't like to use the
word, because of what it really means: technically "transducer" is a generic
term which describes any device which changes energy from one form to another. So it would
be just as accurate to describe an audio speaker or a microphone as a transducer as would
a guitar pickup. So I'll just avoid it in favor of "pickup."

MAGNETIC SOUNDHOLE PICKUPS
Many of the solutions to the guitar amplification problem will become obvious if we take a
step back and examine how a guitar produces sound. Three distinct sources of sound on the
guitar can be described. Each is best "picked up" by a specific type of pickup.
First, the strings alone are producing sound. The sound of the strings is the result of
the natural "internal" resonances of the strings plus a complex overlay of
"crosstalk" from adjacent strings and feedback from the moving soundbox (the
strings shake the guitar; and the guitar then shakes the strings). As complex as this
"information" is (because it has yet to affect the "nearfield" around
the guitar--as well as the air and body/wood resonances of the guitar itself) it is the
simplest and least troublesome information source on the guitar, and many stage performers
who want to play loud or are surrounded by loud instruments will attempt to limit the
"information input" into the amplification system by placing a magnetic pickup
directly under the strings--usually in the sound hole. The decision to put a magnetic
pickup (like a Shadow or a Sunrise) entails both advantages and costs. The advantages are
simplicity, power, clarity and virtually no feedback problems. The cost: a
"flat" sound with little warmth or dimension. The warmth and dimension, however
can be added at the board with a touch of reverb, compression, and other alchemy. Some of
the modern soundhole pickups are very popular because they add some proprietary circuitry
that supplies some of the warmth and depth which are typically lacking in such systems.
Another drawback is that these pickups work by having a metallic conductor (a steel
string) cutting across the magnetic field of the pickup's magnetic poles. This generates
the minute voltage which is carried to the amplifier. Nylon strings won't work, so you
won't find soundhole pickups in classic guitars. Oh, yes, there is a third sound
production mechanism on the guitar, best picked up by a microphone. I'll deal with it in
the next installment.

CONTACT PICKUPS
Well, the strings drive the soundboard, resonances flood the guitar, and the music rises
off the wood "like heat from a skillet" (colorful, evocative analogy thanks to
Tim White). The sound rising from the moving wood surfaces on the guitar can be directly
heard by so-called "contact" pickups: small, inexpensive devices--some as small
as dots (they were first developed for the spying industry!), which are actually adhered
to the plates and when moved by them, generate a minute voltage which is then fed to the
amplifier. They are at best, very "directional" in the sense that they react to
the acoustic activity present only in the immediate region where they are located. You
usually must move them from site to site looking for the sweet spot, each spot eliciting
either a subtle or dramatic difference in response. Unfortunately, you can never be quite
sure that the response you are getting is the best one on a particular instrument, so you
usually must settle. For many instruments, particularly the smaller ones, contact pickups
are the only option: they are small, unobtrusive, cheap, work for both nylon and steel
strings, and produce a reasonably acceptable response when fulfilling modest amplification
demands. They will fall short in loud environments, however--they can turn the instrument
into a microphone! But for $40 - $50 they're a salvation for moderate-requirement poverty
jobs.

SADDLE STRIP PICKUPS
A better solution -- with an accompanying increment in cost -- are the piezo/ceramic strip
pickups, which are placed in the bridge, under the saddle. These are by far the most
popular pickups. They succeed where the "contact" and magnetic pickups fall
short, in that due to their placement (precisely at the interface between the strings and
the guitar) they receive a lot more information than the two others, and produce a more
complex, balanced sound.

There are a number of technical problems which traditionally have dogged these
pickups, however. Strip pickups respond to acceleration (shaking) in one direction, others
to two; some to pressure. Thus, they are prone to string-to-string volume-balance problems
usually caused by inexpert or inexact installation: they have to fit just right, the
string pressure must be distributed adequately and evenlyover the pickup; the saddle must
be shaped just right and fit the slot not too tightly or too loosely, and must protrude by
the right amount. Clearly, they require thoughtful installation for optimum results.
Regardless of the care exercised in their installations, traditional contact and strip
pickups have a common drawback: impedance mismatch. This is a result of History: guitar
amplifiers were originally made for electric guitars, which are invariably supplied with
magnetic coil pickups which produce their voltage at a low impedance of about 500k ohms.
Contact and strip piezo/ceramic pickups typically produce their voltage at impedance
measured in millions of ohms. Thus when you plug a contact or strip pickup into your
typical Fender amp, which is expecting a low impedance from a magnetic pickup, the result
is a hot, "honky" sound (like somebody singing with their nose plugged up). The
rather harsh, raspy sound is a result of this impedance mismatch, which actually does the
same thing as if you turned the amp treble and midrange knobs to 10--all the time.
(Actually, tone knobs are really impedance "mismatching" devices).

The solution: a more expensive upgrade. Add a little black box, called a buffer
preamp (which requires a battery to power it) to the line, lowering the pickup's output
impedance and bringing it closer to the input impedance that most guitar amplifiers are
expecting. The honky sound is gone and in its place, a smooth, pleasing, balanced sound.
But now that you have a battery in the system, you might as well take advantage of its
presence to furnish a complement of bells and whistles: treble/bass boosting,
equalization, and so forth. The only problem left is where to actually put the darn
things. Most modern powered pickup systems have simplified installation by smoothly fusing
the preamp with the output jack (Highlander) or by supplying a flexible strip that can be
fed through a hole in the saddle slot so you don't have to solder anything (Baggs).

Where to put the bells and whistles is a problem. It is unspeakably horrible to
cut a huge window sized hole in a guitar for a transducer effect box, and only slightly
less horrible to drill holes for volume and tone knobs. It's bad enough that you must
drill an oversized hole in the butt of the guitar to plug the thing in. So I usually beg
the guitar owner to put everything on an outboard effects box which clips to the belt. In
many cases, the interior battery can be dispensed with using an outboard box. Even though
the latest strip pickup systems use infinitesimally small amounts of battery juice, and
the engineers have gotten the battery-replacement requirements down to yearly or even
bi-yearly, I'm bumping into more and more people who just don't want batteries installed
inside their guitars, period. Batteries perversely insist on bumping loose and rattling
around at the wrong time, or the cheezy wire clips tend to fail and shut their guitar off,
again in the middle of a big show. Also, since it's near impossible to stash the wiring
neatly when installing aftermarket through the soundhole, the wires tend to slosh around
annoyingly all the time and even cause resonant "shadow" buzzes inside the
guitar which drive people like me crazy. So I just love it when I can persuade people to
use outboard effects/buffer preamp/power supply boxes that clip to their belt. By now,
most pickup companies offer some variation on this theme.

That's enuf for now. I'll save my final comments on internal microphones, comments
about tap tones, and other subscriber inquiry responses for next week.